1. Field
The following description relates to a method of designing a codebook that may be used in a multiple input multiple output (MIMO) communication system. More particularly, the description relates to a technology that may design a network codebook that may be shared by one or more base stations, and a method to use the network codebook.
2. Description of Related Art
With the increasing number of multimedia devices in use there is a continuing need for upgraded multimedia services that can support high quality and high speed data transmission in a wireless communication environment. A multiple input multiple output (MIMO) communication system may use multiple channels in a spatial area. The MIMO communication system may include at least one base station, or a plurality of base stations. Generally, the MIMO communication system may be classified into a multi-user MIMO communication system that may include a plurality of users and a single base station. In the current state of the art, there are also single-user MIMO communication systems that may include a single user and a single base station.
In a MIMO communication system, at least one base station and the connected terminals may use a codebook. A particular space may be quantized into a plurality of vectors or matrices. The plurality of vectors or matrices that are generated by quantizing the particular space may be stored, as the codebook, in the at least one base station and the terminals.
For each terminal a channel may be formed between the base station and the terminal. Each of the terminals may select a matrix from the matrices included in the codebook. Each of the terminals may select a vector from the vectors included in the codebook. The selection may be based on the channel that is formed between the base station and the terminals. The base station may also recognize the selected matrix or vector using the codebook. The selected matrix or vector may be used where the base station generates a precoding matrix or a precoding vector.
The plurality of base stations may be spatially separated from each other by, for example, 10 meters, 100 meters, 1000 meters, 5 kilometers, or other desired distance, and may serve as terminals in cooperation with each other or without mutual cooperation. Often times, fading will occur as a wireless signal travels between a base station and a terminal and between terminals themselves. The term fading is used to describe fluctuations in a transmitted wireless signal. For spatially separated networks, large scale fading can occur due to any number of factors, for example, reflection, diffraction, scattering, and the like.